1. Field of the Invention
The present invention relates to an ink-jet recording head and an ink-jet recording apparatus wherein a plurality of nozzle rows for discharging ink of different colors are arrayed in approximately a straight line in approximately the same direction as the transporting direction of a recording medium. The present invention also relates to electronic equipment comprising an ink-jet recording apparatus.
2. Description of the Related Art
The ink-jet recording method performs recording of dots by forming flying droplets of ink which is a recording liquid and landing these on a recording medium such as paper or the like, and has a low noise factor due to being a non-contact method. Also, high resolution and high-speed recording is enabled by the increased density of the ink discharge nozzles, and further, no special processing such as developing or fixing is necessary for recording media such as plain paper or the like, so high-quality images can be obtained at low costs. Accordingly, this method has become widespread in recent years.
Particularly, on-demand type ink-jet recording apparatuses can be easily arranged to deal with color, and further the apparatus itself can be easily reduced in size and complexity, so widespread demand thereof in the future is expected. Also, as such color becomes commonplace, even higher image quality and speed is being required.
With such ink-jet recording apparatuses, serial scan apparatuses comprise a carriage upon which are mounted a recording head and ink tanks, and a transporting device for transporting the recording medium, wherein the recording head upon which multiple ink discharging orifices (nozzles) are arrayed in the transporting direction of the recording medium (i.e., the sub-scanning direction) is serially scanned in a direction orthogonal to the sub-scanning direction (i.e., the main scanning direction) using the carriage, and following completion of recording one line, the recording medium is transported by an amount equivalent to one pitch, following which the next image is recorded on the recording medium which has stopped again, and this is repeated, until recording is carried out on the entire recording medium.
Also, in the case of color recording, a recording head for the three colors yellow (Y), magenta (M), and cyan (C), or the four colors of these with black (B), and ink tanks thereof, are mounted on the carriage to carry out recording.
There are two types of nozzle row array configurations for such color recording heads; parallel types wherein the color nozzle rows are arrayed in parallel, and inline types wherein the color nozzle rows are arrayed inline.
Parallel types wherein the color nozzle rows are arrayed in parallel in the carriage scanning direction are generally suitable for high-speed printing, though this depends on the length of the nozzle rows. This is due to the fact that each of the colors can be discharged and overlaid in a single scan of the carriage. However, the parallel type has a problem in that the order in which the droplets of ink land differs between scanning in one direction and scanning in the returning direction, in the event that recording is performed both coming and going, so the coloring changes depending on the direction in which the carriage is traveling. There also is a problem with types which discharge ink using thermal energy in that driving heater boards must be arrayed in high precision for each of the color nozzle rows.
On the other hand, inline types wherein the color nozzle rows are arrayed inline in the transporting direction of the recording medium are advantageous with regard to reduction in the size of the head itself, and also manufacturing is relatively easy, which is advantageous in the area of costs as well.
Thus, inline type recording heads are generally advantageous regarding reduction in size and costs.
Now, in recent years, there have been increased demands for printers for PDAs, digital cameras, etc., requiring further reduction in size and increase in speed of the recording heads for ink-jet recording apparatuses.
While inline type recording heads are suitable for reduced size as described above, there are the following problems which occur in the event that the recording head scanning speed is increased (i.e., the driving frequency is increased) to perform high-speed printing.
Increased head scanning speed means that the amount of time from the current scan to the next scan is reduced, and accordingly the time from discharging ink of one color to the time of discharging the next ink color is also reduced. Consequently, bleeding at the boundary between the dots on the recording medium, or mixing of colors on the recording head face at the time of suctioning recovery, occurs, markedly deteriorating the image quality.
The present invention has been made in light of the above-described problems with the conventional art, and accordingly it is an object of the present invention to provide an ink-jet recording head, ink-jet recording apparatus, and electronic equipment, capable of preventing bleeding on the recording medium and mixing of colors on the recording head in cases of printing at high speeds with in-line type recording heads, so as to obtain high-quality images at low costs with simple modifications.
According to a first aspect of the present invention, an ink-jet recording head comprises a plurality of nozzle rows for discharging ink of different colors arrayed in approximately a straight line in approximately the same direction as a transporting direction of a recording medium, with images being recorded on the recording medium by scanning in a direction orthogonal to the arrayed direction of the nozzle rows, wherein, of the nozzle rows of different colors for discharging ink, the positioning spacing of the nozzle rows of different colors is set so as to be greater than the shortest nozzle row.
With the present invention, the positioning spacing of the nozzle rows for each color is set so as to be greater than the length of the nozzle rows of different colors for discharging ink, so a great amount of time can be purchased between the current scan and the next scan, thereby preventing bleeding on the recording medium and mixing of colors on the recording head.
A dummy nozzle may be positioned between nozzle rows for discharging ink of different colors.
The positioning spacing of the nozzle rows of different colors converted into the number of nozzles, and the length of the nozzle rows of different colors converted into the number of nozzles, may be set so as to be multiples of a natural number n, and also the amount of transporting the recording medium per time converted into the number of nozzles may be a multiple of the natural number n.
The plurality of nozzles arrayed in each of the nozzle rows may be disposed in a staggered array.
According to another aspect of the present invention, an ink jet recording apparatus comprises the above-described ink-jet recording head.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.